Add CLI documentation

[BenasB]

• Start using standard flag package in CLI
  • Support flags for commands
  • support -h (and --h, --help, -help) flag to print out command description, usage and flag explanations.
• Create a task in Taskfile to extract, parse and transform the help data from the CLI binary to .md pages.
• Add CLI documentation generation to GitHub Actions workflow

CLI help example

$ bx2cloud container exec -h
bx2cloud container exec: Starts a shell process inside a specified container or executes a specific command, if specified
usage: bx2cloud container exec <id> [cmd]
flags: none

$ bx2cloud -h
bx2cloud subcommands:
  version
  network
  subnetwork
  container
flags:
  -t string
        API target <host>:<port> (default "localhost:8080")

Docusaurus example

---
title: "container exec"
custom_edit_url: null
---
# bx2cloud container exec

Starts a shell process inside a specified container or executes a specific command, if specified

## Usage

```
bx2cloud container exec <id> [cmd]
```

---
title: "Global flags"
sidebar_position: 1
custom_edit_url: null
---
# Global flags

These flags can be used with any command.

## Usage

```
bx2cloud -t 127.0.0.1:9876 version
```

## Flags

| Flag | Type | Description | Default |
|------|------|-------------|---------|
| `-t` | `string` | API target `<host>`:`<port>` | localhost:8080 |

Unrelated changes

• Change slug of autogenerated TF provider reference slug to be nested under /terraform/ instead of /category/. Also move the content from /terraform/autogenerated file directory to /terraform/reference
• Change example command in CLI docs to be bx2cloud version